Techniques for manufacturing highly bright light-emitting diodes (LEDs) and white LED shave become matured, allowing the LEDs to be widely applied to desk lamps, projector lamps, street lamps, etc. Now, LED lamps tend to gradually replace the incandescent lamps with tungsten filament and become a major light source for indoor illumination.
In the traditional incandescent lamp, a large current is supplied to flow through the tungsten filament, so that the tungsten filament is heated to glow and emit light. Unlike the conventional tungsten filament lamp, the LED is a semiconductor element. When the electrons and holes in the semiconductor material of the LED join one another to release energy, light is emitted. Therefore, only a very low current is needed to excite the LED to emit very bright light.
The LED consumes less power and is therefore energy-saving and can reduce the greenhouse effect, compared to the traditional incandescent lamp. However, the LED also encounters the problem of heat dissipation. The heat generated by the LED increases with the increased brightness of the emitted light. In the event the generated heat is not timely removed from the LED, it would adversely shorten the service life of the LED, and even burn out the electronic elements nearby the LED. Therefore, it has become a quite important issue in the LED field to find a way to efficiently dissipate the heat generated by the LED.
FIG. 1 shows a conventional heat sink for LED, which includes a radiating fin assembly 10, a base 11, and an LED module 12. The radiating fin assembly 10 consists of a plurality of radiating fins 100 connected at an end to an upper surface of the base 11 by welding. The LED module 12 is arranged beneath a lower surface of the base 11. When the LED module 12 emits visible light and generates heat, the heat is conducted via the base 11 to the radiating fin assembly 10. Through heat exchange between the radiating fins 100 and air flowing through the radiating fin assembly 10, heat conducted to the radiating fins 100 is carried away by the air and dissipates into ambient environment. However, in the process of heat dissipating, due to the base 11 located between the LED module 12 and the radiating fin assembly 10, air below the LED module can not flow to the radiating fin assembly 10 directly, but has to pass by outer sides of the base 11. As a result, the air is distributed in different directions without being concentrated to the radiating fin assembly 10. That is, the heat-exchange is conducted only between part of the air and the radiating fin assembly 10. Therefore, heat conducted to the radiating fin assembly 10 could not be effectively removed to thereby result in poor heat dissipating effect. Moreover, the above-described conventional heat sink also has limited heat dissipating areas. In brief, the conventional heat sink for LED has the following disadvantages: (1) providing only very limited heat-dissipating areas; and (2) having poor heat-dissipating effect.